In the area of small-sized tube inspection, the prior art includes an eye test, a thickness measurement method, and others.
An eye test is a method of visually inspecting a physical state of a surface of an inspection object, such as corrosion, erosion, and abrasion, with the naked eye or by using an auxiliary device such as a telescope.
The eye test is advantageously used to inspect an inspection object without regard to the size of the inspection object, irrespective of a material of which the inspection object is formed, such as ferrous and nonferrous metals and magnetic materials, but cannot be used to inspect defects occurring inside pipelines.
A thickness measurement method is a method for measuring the degree of wall-thinning of a pipeline material using ultrasonic waves.
The thickness measurement method is used to measure the degree of corrosion and wall-thinning in the interior of the pipeline through measurement of the thickness of the pipeline. A measurement device is portable and convenient in terms of the use thereof and is able to detect internal defects in pipelines, but requires an excessive amount of time in a case of inspecting a large pipeline area.
In addition, pipeline inspection devices according to the related art may inspect pipelines by forcibly increasing a narrow gap between pipelines when a sensor cannot be attached to the narrow gap, and in this case, the pipelines may be deformed, causing damage to the pipelines.